Low power, high performance, heterogeneous, scalable processor architecture

ABSTRACT

One embodiment of the present includes a heterogeneous, high-performance, scalable processor having at least one W-type sub-processor capable of processing W bits in parallel, W being an integer value, at least one N-type sub-processor capable of processing N bits in parallel, N being an integer value smaller than W by a factor of two. The processor further includes a shared bus coupling the at least one W-type sub-processor and at least one N-type sub-processor and memory shared coupled to the at least one W-type sub-processor and the at least one N-type sub-processor, wherein the W-type sub-processor rearranges memory to accommodate execution of applications allowing for fast operations.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.12/782,431, entitled “LOW POWER, HIGH PERFORMANCE, HETEROGENEOUS,SCALABLE PROCESSOR ARCHITECTURE” and filed on May 18, 2010, now allowed,which is a continuation of U.S. patent application Ser. No. 11/180,068,entitled “LOW POWER, HIGH PERFORMANCE, HETEROGENEOUS, SCALABLE PROCESSORARCHITECTURE” and filed on Jul. 12, 2005, now U.S. Pat. No. 7,721,069,which claims the benefit of U.S. Provisional Patent Application No.60/587,691, entitled “Quasi-Adiabatic Programmable or COOL ProcessorsArchitecture” and filed on Jul. 13, 2004 and the benefit or U.S.Provisional Patent Application No. 60/598,417, entitled “Quasi-AdiabaticProgrammable Processor Architecture” and filed on Aug. 2, 2004, theentire disclosures of all of which are hereby incorporated by referenceherein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to the field of processors and moreparticularly, to processors having low power consumption, highperformance, low die area, and flexibly and scalably employed inmultimedia and communications applications.

2. Description of the Prior Art

With the advent of the popularity of consumer gadgets, such as cell ormobile phones, digital cameras, iPOD® and personal data assistances(PDAs), many new standards for communication with these gadgets havebeen adopted by the industry at wide. Some of these standards includeH264, Moving Picture Experts Group (MPEG4), Ultra Wide Band (UWB),BLUETOOTH®, 2G/2.5G/3G/4G, Global Positioning System (GPS), MP3 andSecurity. iPOD® is a registered trademark owned by Apple Computers, Inc.BLUETOOTH® is a registered certification mark owned by Bluetooth Sig,Inc. However, an emerging problem is the use of different standardsdictating communications of and between different gadgets requiringtremendous development effort. One of the reasons for the foregoingproblem is that no processor or sub-processor, currently available inthe marketplace, is easily programmable for use by all digital devicesand conforming to the various mandated standards. It is only a matter oftime before this problem grows as new trends in consumer electronicswarrant even more standards adopted by the industry in the future.

One of the emerging and, if not, current, requirements of processors islow power consumption yet the ability to cause execution of codesufficient to process multiple applications. Current power consumptionis on the order of sub-hundreds of milliwatts per application, whereas,the goal is to be under sub-hundreds of milliwatts for executingmultiple applications. Another requirement of processors is low cost.Due to the wide utilization of processors in consumer products, theprocessor must be inexpensive to manufacture, otherwise, its use in mostcommon consumer electronics is not pragmatic.

To provide specific examples for current processor problems, problemsassociated with RISCs, which are used in some consumer products,microprocessors, which are used in other consumer products, digitalsignal processors (DSPs), which are used in yet other consumer productsand application specific integrated circuits (ASICs), which are used instill other consumer products, and some of the other well-knowprocessors, each exhibiting a unique problem are briefly describedbelow. These problems along with advantages of using each are outlinedbelow in a “Cons” section discussing the disadvantages thereof and a“Pros” section discussing the benefits thereof.

A. RISC/Super Scalar Processors

RISC and Super Scalar processors have been the most widely acceptedarchitectural solution for all general purpose computing. They are oftenenhanced with application specific accelerators for solving certainspecialized problems within the context of a general solution.

Examples include: ARM series, ARC series, StrongARM series, and MIPSseries.

Pros:

-   -   Industry wide acceptance has lead to a more matured tool chain        and wide software choices    -   A robust programming model has resulted from a very efficient        automatic code generator used to generate binaries from high        level languages like C.    -   Processors in the category are very good general purpose        solutions.    -   Moore's Law can be effectively used for increasing performance.

Cons:

-   -   The general purpose nature of the architecture does not leverage        common/specific characteristics of a set or sub-set of        applications for better price, power and performance.    -   They consume moderate to high amounts of power with respect to        the amount of computation provided.    -   Performance increase is mostly achieved at the expense of        pipeline latency which adversely affects several multimedia and        communication algorithms.    -   Complicated hardware scheduler, sophisticated control mechanisms        and significantly reduced restrictions for more efficient        automatic code generation for general algorithms have made this        category of solutions less area efficient.

B. Very Long Instruction Word (VLIW) and DSPs

VLIW architectures eliminated some of the inefficiencies found in RISCand Super Scalar architectures to create a fairly general solution inthe digital signal processing space. Parallelism was significantlyincreased. The onus of scheduling was transferred from hardware tosoftware to save area.

Examples include: TI 64xx, TI 55xx, StarCore SC140, ADI SHARC series.

Pros:

-   -   Restricting the solution to the signal processing space improved        3P in comparison with RISC and Super Scalar architectures    -   VLIW architectures provide higher level of parallelism relative        to RISC and superscalar architectures.    -   An efficient tool chain and industry wide acceptance was        generated fairly rapidly.    -   Automatic code generation and programmability are showing        significant improvements as more processors designed for signal        processing fall into this category.

Cons:

-   -   Although problem solving capability is reduced to the digital        signal processing space, it is too broad for a general solution        like VLIW machine to have efficient 3P.    -   Control is both expensive and power consuming especially for        primitive control code in many multimedia and communication        applications.    -   Several power and area inefficient techniques were used to make        automatic code generation easy. Strong reliance on these        techniques by the software community is carrying forward this        inefficiency from generation to generation.    -   VLIW architectures are not well suited for processing serial        code.

C. Reconfigurable Computing

Several efforts in industry and academia over the last 10 years werefocused towards making a flexible solution with ASIC like price, powerand performance characteristics. Many have challenged existing andmatured laws and design paradigms with little industry success. Most ofthe attempts have been in the direction of creating solutions based oncoarser grain FPGA like architectures.

Pros:

-   -   Some designs restricted to a specific application while        providing needed flexibility within that application proved to        be price, power, performance competitive    -   Research showed that such restricted yet flexible solutions can        be created to address many application hotspots.

Cons:

-   -   Several designs in this space did not provide an efficient and        easy programming solution and therefore was not widely accepted        by a community adept in programming DSPs.    -   Automatic code generation from higher level languages like C was        either virtually impossible or highly inefficient for many of        the designs.    -   3P advantage was lost when an attempt was made to combine        heterogeneous applications using one type of interconnect and        one level of granularity. Degree of utilization of the provided        parallelism suffered heavily.    -   Reconfiguration overhead was significant in 3P for most designs.    -   In many cases, the external interface was complicated because        the proprietary reconfigurable fabric did not match industry        standard system design methodologies.    -   Reconfigurable machines are uni-processors and rely heavily on a        tightly integrated RISC even for processing primitive control.

D. Array of Processors

Some recent approaches are focused on making reconfigurable systemsbetter suited to process heterogeneous applications. Solutions in thisdirection connect multiple processors optimized for either one or a setof applications to create a processor array fabric.

Pros:

-   -   Different processors optimized for different sets of        applications when connected together using an efficient fabric        can help solve a wide range of problems.    -   Uniform scaling model allows number processors to be connected        together as performance requirements increase.    -   Complex algorithms can be efficiently partitioned.

Cons:

-   -   Although performance requirements may be adequately answered,        power and price inefficiencies are too high.    -   The programming model varies from processor to processor. This        makes the job of the application developer much harder.    -   Uniform scaling of multiple processors is a very expensive and        power consuming resource. This has shown to display some        non-determinism that may be detrimental to the performance of        the entire system.    -   The programming model at the system level suffers from        complexity of communicating data, code and control information        without any shared memory resources—since shared memory is not        uniformly scalable.    -   Extensive and repetitive glue logic required to connect        different types of processors to a homogeneous network adds to        the area inefficiencies, increases power and adds to the        latency.

In light of the foregoing, there is a need for a low-power,inexpensive,efficient, high-performance, flexibly programmable,heterogenous processor for allowing execution of one or more multimediaapplications simultaneously.

SUMMARY OF THE INVENTION

Briefly, one embodiment of the present includes a heterogeneous,high-performance, scalable processor having at least one W-typesub-processor capable of processing W bits or greater in parallel, Wbeing an integer value, at least one N-type sub-processor capable ofprocessing N bits in parallel, N being an integer value smaller than W.The processor further includes a shared bus coupling the at least oneW-type sub-processor and at least one N-type sub-processor and memoryshared coupled to the at least one W-type sub-processor and the at leastone N-type sub-processor, wherein the W-type sub-processor rearrangesdata bytes in transit to or from memory to accommodate execution ofapplications allowing for fast operations.

IN THE DRAWINGS

FIG. 1 shows an application 10 is shown with reference to a digitalproduct 12 including an embodiment of the present invention

FIG. 2 shows an exemplary integrated circuit 20 including aheterogenous, high-performance, scalable processor 22 coupled to amemory controller and direct memory access (DMA) circuit 24 inaccordance with an embodiment of the present invention.

FIG. 3 illustrates further details of the processor 20 in accordancewith an embodiment of the present invention.

FIG. 4 shows a high level block diagram of the blocks or structureincluded within one of the W type blocks, such as the block 74 or 76, inaccordance with an embodiment of the present invention.

FIG. 5 shows a block diagram of the circuit blocks included in the block402, in accordance with an embodiment of the present invention.

FIG. 6 shows in greater detail the general structure employed forregister files and forwarding inside macro functional units,specifically in blocks 402, 404, 406, and 408.

FIG. 7 shows further details of the block 408, in high-level blockdiagram form and accordance with an embodiment of the present invention.

FIG. 8 shows further details, in block diagram form, of the block 404,in accordance with an embodiment of the present invention.

FIGS. 9 and 10 shows further details of the block 404, particularly withrespect to performing permutations.

FIG. 11 shows further details of the components of the block 406, inblock diagram form and accordance with an embodiment of the presentinvention.

FIG. 12 shows a high level block diagram of the details of the block 78in accordance with an embodiment of the present invention.

FIG. 13 shows still further details of the block 78, in high level blockdiagram form, in accordance with an embodiment of the present invention.

FIG. 14 shows further details of the block 1322 in accordance with anembodiment of the present invention.

FIG. 15 shows further details of the circuitry included in the block1324, in high-level block diagram form and accordance with an embodimentof the present invention.

FIG. 16 shows a block diagram of a reduction circuit block 1602,included within the block 1520, in accordance with an embodiment of thepresent invention.

FIG. 17 shows further details of the circuitry included in the block1326, in high-level block diagram form and accordance with an embodimentof the present invention.

FIG. 18 shows further details of the circuitry included in the block1330, in high-level block diagram form and accordance with an embodimentof the present invention.

FIG. 19 shows further details of the circuitry included in the block1332, in high-level block diagram form and accordance with an embodimentof the present invention.

FIG. 20 shows further details of the circuitry included in the block1334, in high-level block diagram form and accordance with an embodimentof the present invention.

FIG. 21 shows an example of programming flow and tools using theprocessor 22 in accordance with an embodiment of the present invention.

FIG. 22 shows an example of the scalability of embodiments of thepresent invention.

FIG. 23 shows the a chart presenting some of the benefit the scalabilityof the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIG. 1, an application 10 is shown with reference to adigital product 12 including an embodiment of the present invention.FIG. 1 is intended to provide the reader with a perspective regardingsome, but not necessarily all, of the advantages of a product, whichincludes an embodiment of the present invention relative to thoseavailable in the marketplace.

Accordingly, the product 12 is a converging product in that itincorporates all of the applications that need to be executed by today'smobile phone device 14, digital camera device 16, digital recording ormusic device 18 and PDA device 20. The product 12 is capable ofexecuting one or more of the functions of the devices 14-20simultaneously yet utilizing less power.

The product 12 is typically battery-operated and therefore consumeslittle power even when executing multiple applications of theapplications executed by the devices 14-20. It is also capable ofexecuting code to effectuate operations in conformance with a multitudeof applications including but not limited to: H264, Moving PictureExperts Group (MPEG4), Ultra Wide Band (UWB), BLUETOOTH®, 2G/2.5G/3G/4G,Global Positioning System (GPS), MP3 and Security.

FIG. 2 shows an exemplary integrated circuit 20 including aheterogenous, high-performance, scalable processor 22 coupled to amemory controller and direct memory access (DMA) circuit 24 inaccordance with an embodiment of the present invention. Further shown inFIG. 2, the processor 22 is coupled to interface circuit 26 through ageneral purpose bus 30 and to the interface circuit 28 through a generalpurpose bus 31 and further coupled, through the bus 30, to a generalpurpose processor 32 through the bus 31. The circuit 20 is further shownto include a clock reset and power management 34 for generating a clockutilized by the remaining circuits of the circuit 10, a reset signalutilized in the same manner and circuitry for managing power by thesame. There is further included in the circuit 20, a Joint Test ActionGroup (JTAG) circuit 36. JTAG is used as a standard for testing chips.

The interface circuit 26 shown coupled to the bus 30 and interfacecircuit 28, shown coupled to the bus 31, include the blocks 40-66, whichare generally known to those of ordinary skill in the art and used bycurrent processors.

The processor 22, which is a heterogeneous multi-processor, is shown toinclude shared data memory 70, shared data memory 72, a CoolWsub-processor (or block) 74, a CoolW sub-processor (or block) 76, aCoolN sub-processor (or block) 78 and a CoolN sub-processor (or block)80. Each of the blocks 74-80 has associated therewith an instructionmemory, for example, the CoolW block 74 has associated therewith aninstruction memory 82, the CoolW block 76 has associated therewith aninstruction memory 84, CoolN block 78 has associated therewith aninstruction memory 86 and the CoolN block 80 has associated therewith aninstruction memory 88. Similarly, each of the blocks 74-80 hasassociated therewith a control block. The block 74 has associatedtherewith a control block 90, the block 76 has associated therewith acontrol block 92, the block 78 has associated therewith a control block94 and the block 80 has associated therewith a control circuit 96. Theblock 74 and 76 are designed to generally operate efficiently for 16,24, 32 and 64-bit operations or applications, whereas, the blocks 78 and80 are designed to generally operate efficiently for 1, 4, or 8-bitoperations or applications.

The blocks 74-80 are essentially sub-processors and the CoolW blocks 74and 76 are wide (or W) type of blocks, whereas, the CoolN blocks 78 and80 are narrow (or N) type of blocks. Wide and narrow refers to therelative number of parallel bits processed or routed within asub-processor and that gives the heterogeneous characteristic of theprocessor 22. Furthermore, the circuit 24 is coupled directly to one ofthe sub-processors, i.e. one of the blocks 74-80 resulting in the lowestlatency path through the sub-processor to which it is coupled. In FIG.2, the circuit 24 is shown directly coupled to the block 76 although itmay be coupled to any of the blocks 74, 78 or 80. Higher priority agentsor tasks may be assigned to the block which is directly coupled to thecircuit 24.

It should be noted that while four blocks 74-80 are shown, other numberof blocks may be utilized, however, utilizing additional blocks clearlyresults in additional die space and higher manufacturing costs.

Complicated applications requiring great processing power are notscattered in the circuit 20, rather, they are grouped or confined to aparticular sub-processor or block for processing, which substantiallyimproves power consumption by eliminating or at least reducing wire(metal) or routing lengths thereby reducing wire capacitance.Additionally, utilization is increased and activity is reducedcontributing to lower power consumption.

The circuit 20 is an example of silicon on chip (or SoC) offeringQuasi-Adiabatic Programmable sub-Processors for multimedia andcommunications applications, two types of sub-processors are included,as previously indicated: W type and N type. W type or Wide typeprocessor is designed for high Power, Price, Performance efficiency inapplications requiring 16, 24, 32 and 64-bits of processing. N type orNarrow type processor is designed for high efficiency in applicationsrequiring 8, 4 and 1-bit of processing. While these bit numbers are usedin the embodiments of the present invention, by way of figures anddescription, other number of bits may be readily employed.

Different applications require different performance or processingcapabilities and are thus, executed by a different type of block orsub-processor. Take for instance, applications that are typicallyexecuted by DSPs, they would be generally be processed by W typesub-processors, such as the blocks 74 or 76 of FIG. 2 because theycharacteristically include commonly occurring DSP kernels. Suchapplications include, but are not limited to, fast fourier transform(FFT) or inverse FFT (IFFT), Adaptive finite impulse response (FIR)filters, Discrete Cosine transform (DCT) or inverse DCT (IDCT),Real/Complex FIR filter, IIR filter, resistance capacitor Root RaiseCosine (RRC) filter, Color Space Converter, 3D Bilinear Texture Mapping,Gouraud Shading, Golay Correlation, Bilinear Interpolation,Median/Row/Column Filter, Alpha Blending, Higher-Order SurfaceTessellation, Vertex Shade (Trans/Light), Triangle Setup, Full-ScreenAnti-aliasing and Quantization.

Other commonly occurring DSP kernels can be executed by N typesub-processors, such as blocks 78 and 80 and include, but are notlimited to, Variable Length Codec, Viterbi Codec, Turbo Codec, CyclicRedundancy Check, Walsh Code Generator, Interleaver/De-Interleaver,LFSR, Scrambler, De-spreader, Convolution Encoder, Reed-Solomon Codec,Scrambling Code Generator, and Puncturing/De-puncturing.

Both W and N type sub-processors are capable of keeping net activity andthe resulting energy per transition low while maintaining highperformance with increased utilization in comparison with existingarchitectural approaches like RISC, Reconfigurable, Superscalar, VLIWand Multi-processor approaches. The sub-processor architecture of theprocessor 22 reduces die size resulting in an optimal processingsolution and includes a novel architecture referred to as“Quasi-Adiabatic” or “COOL” architecture. Programmable processors inaccordance therewith are referred to as Quasi-Adiabatic Programmable orCOOL Processors.

Quasi-Adiabatic Programmable or COOL Processors optimize data path,control, memory and functional unit granularity to match a finite subsetof applications, as described previously. The way in which this isaccomplished will be clear relative to a discussion and presentation offigures relating to the different units or blocks or circuits and theirinter-operations of the processor 22, as presented below.

“Quasi-Adiabatic Programmable” or Concurrent Applications ofheterOgeneous intercOnnect and functionaL units (COOL) Processors. Interm of thermodynamics, Adiabatic Processes do not waste heat andtransfer all the used energy to performing useful work. Due to thenon-adiabatic nature of existing standard processes, circuit design, andlogic cell library design techniques, one can not ever make an AdiabaticProcessors. However, among the possible different possible processorarchitecture some may be closer to Adiabatic. The various embodiments ofthe present invention show a class of processor architectures which aresignificantly closer to Adiabatic as compared to the architectures ofprior art, while they are, nevertheless, programmable. They are referredto as “Quasi-Adiabatic Programmable Processors”.

The integrated circuit 20 allows as many applications as can besupported by the resources within the processor 22 to be executedtogether or concurrently and the number of such applications far exceedsthat which is supported by current processors. Examples of applicationsthat can be simultaneously or concurrently executed by the integratedcircuit 20 include but are not limited to downloading an applicationfrom a wireless device while decoding a movie that has been received,thus, a movie can be downloaded and decoded simultaneously. Due toachieving simultaneous application execution on the integrated circuit20, which has a small die size or silicon real estate as compared to thenumber of applications it supports, costs of manufacturing theintegrated circuit are significantly lower than that which is requiredfor multiple devices of FIG. 1. Additionally, the processor 22 offers asingle programmable framework to a user to implement multiple functions,such as multimedia complex applications. Of important value is theability of the integrated circuit 20 and namely, the processor 22, tosupport future standards adopted by the industry, which are expected tobe of greater complexity than that of today's standards.

Each of the blocks 74-80 can execute only one sequence (or stream) ofprograms at a given time. A sequence of program is referred to afunction associated with a particular application. For example, FFT is atype of sequence. However, different sequences may be dependent on oneanother. For example, an FFT program, once completed may store itsresults in the memory 70 and the next sequence, may then use the storedresult. Different sequences sharing information in this manner or beingdependent upon each other in this manner is referred to as “streamflow”.

In FIG. 2, the memories 70 and 72 each include 8 blocks of 16 kilobytesof memory, however, in other embodiments, different size memory may beutilized.

The instruction memories 82, 84, 86 and 88 are used to storeinstructions for execution by the blocks 74-80, respectively.

FIG. 3 shows further details of the processor 20 in accordance with anembodiment of the present invention. In FIG. 3, the processor 20 isshown to include the sub-processors 74-80, each including an instructioncache 302-308, respectively, for storing instructions processed by therespective sub-processor. The processor 20 is further shown to includean arbitration block 310, a data memory 312, a general purposeinput/output (GPIO) block 314, a shared SoC bus block 316, a radiofrequency (RF) interface with DMA block 318, a DMA controller block 320and a memory controller block 322 coupled in the manner shown in FIG. 3.The data memory 312 serves as storage of data information, which isutilized by the sub-processors and other blocks under the direction ofthe arbitration block 310, which directs operation and data traffic ofthe various structures/blocks shown in FIG. 3. The block 314 regulatesinput and output traffic to and from the processor 22, the block 320controls DMA operations performed by the processor 22, through the bus316, the block 322 controls operations relating to the memory 312,through the bus 316, the block 318 includes circuitry to handle DMAoperations and is able to receive and/transmit RF signals coupledthrough the signal(s) 324.

Optionally, shared registers 326 and 328 cause communication directlybetween two types of sub-processors. For example, in FIG. 3, theregister 326 is shown coupled to the blocks 74 and 78 for causingstorage of information that is to be shared by these blocks, whichfacilitates execution of applications utilizing more than onesub-processor to the tune of expediting the execution thereof.Similarly, the register 328 is shown coupled to the blocks 80 and 76 forthe same function as that of the register 326.

FIG. 4 shows a high level block diagram of the blocks or structureincluded within one of the W type blocks, such as the block 74 or 76, inaccordance with an embodiment of the present invention. As an examplethe block 74 is used in FIG. 4. In FIG. 4 and throughout this document,functional units or macro-blocks with very specific interconnectstructure are presented between components like adders, multipliers,registers and multiplexers. These macro-blocks are referred to as “MacroFunctional Units” or “MFU”. MFUs represent an efficient programmablesubset of one or more commonly occurring operations in a finite set ofmultimedia and communications applications. The high efficiency in themacro-functional units is the result of substituting critical groups ofatomic operations found in target applications with a set of derivedoperations exhibiting far superior performance and power performance. Insome cases, commonly occurring operations have been combined in a uniquemanner to efficiently re-use hardware.

In FIG. 4, the block 74 is shown to include a load/store MFU block 402,a scalar arithmetic logic unit (ALU) and multiply-accumulate (ACC) MFUsblock 406, a vector x MFU block 404, a vector ALU and multiply ACC MFUblock 408 and a local memory 410 coupled together in the manner shown inFIG. 4. The block 402 generates memory addresses and couples the same onthe memory addresses bus 412. Memory data is coupled onto the memorydata bus 414 and is bi-directionally coupled to the blocks 404 and 406.Vector store mask is coupled onto the vector store mask bus 416 andgenerated by the block 404. Further details of each block is presentedand discussed relative to subsequent figures. Prior to such apresentation and discussion, some of the general features and blocks ofthe block 74 are discussed as follows.

The blocks 406 and 408 perform the majority of actual computation ondata. The Load/Store MFU block 402 computes addresses for accesses madeto/from the memory 312 and the memory 410. The Vector X MFU block 404rearranges vector data on its way between the memory 312 and the block408. The Vector X MFU block 404 is also used to generate vector storemasks for vector stores to the memory 312. The block 406 only operateson one piece of data at a given time, whereas, the blocks 404 and 408operate on data in the form of vector. The block 402 provides addressesfor memory accesses. Some computation is performed by the block 402 butit is in the nature of overhead computations.

A machine instruction encodes (as needed) separate operations for thevarious MFU blocks in addition to operations to move data between MFUblocks. All operations in a single instruction are executed in parallel.The Vector X MFU block 404 causes rearranging of vector data andgeneration of vector store masks under the control of separately encodedoperations in instructions. The local memory 410 is used for storinginformation locally to avoid having to access information externally tothe block 74 for every instruction. The bus 412 is coupled to the memory312 through which memory addresses are provided.

The block 402 is shown coupled to the block 44 through a bus 424, theblock 402 is further shown coupled to the block 406 through a bus 426,the block 402 is further shown coupled to the block 410 through the bus428. The blocks 404, 408 and 410 are shown coupled to each other througha vector bus 420 and the blocks 406, 404, 408 and 410 are shown coupledto each other through a scalar bus 422. A bus is generally a group ofwires, each wire coupling a signal wherein the wires are parallel toeach other and thus, capable of coupling signals in parallel. The numberof wires within a bus defines the number of binary bits, which serves asa characteristic of the bus. In FIG. 4, the vector bus 420 is wider thanthe scalar bus 422, i.e. the bus 420 includes more bits or wires thatcan couple more signals, in parallel, compared to the bus 422. Anexample of the ratio of the number of bits of the bus 420 to the bus 422is a factor of 4, for example, in the example where the bus 422 is 32bits, the bus 420 is 4 times 32 bits or 128 bits.

The block 404 also provides vector store mask, which is coupled onto thebus 416.

Memory data is coupled onto the block 406 for computation operations,from the block 402, but vector data is first provided to the block 404 .. . . It is significant to note that the block 404 offers the ability toorganize data in memory to match that which is needed in the computationunit, i.e. the block 408, thereby greatly increasing performance.

FIG. 5 shows a block diagram of the circuit blocks included in the block402, in accordance with an embodiment of the present invention. Theblock 402 is shown to include an address block 502, a circular bufferregister block 504, an address generator block 508, an address generatorblock 506, a multiplexer (mux) 510 and a mux 512 coupled together in themanner shown in FIG. 5.

The block 502 is coupled to other blocks of the block 402, as shown inFIG. 4 and stores addresses. The block 504 serves to store a circularbuffer range in one of the circular buffer registers (block 504). Theblocks 506 and 508 cause an address computation to wrap around within acircular buffer range when requested by the program. The arrows leadinginto the block 504 allow those registers to be loaded. Namely, the block506 serves to modify the addresses generated by the block 504 or addressreceived from the block 406 or even the addresses generated from theblock 502, while the block 508 serves to modify addresses received fromthe block 502 and/or the block 406 and even the block 504.

The address registers of the block 402 and circular buffer registers ofthe block 404 provide inputs to the address generators of the blocks 506and 508. In the case of the address registers of the block 402, thoseinputs are previously stored addresses, while for the circular bufferregisters of the block 404, those inputs are information about circularbuffers.

The blocks 506 and 508 serve to modify addresses. Namely, the block 506serves to modify the addresses generated by the block 504 or addressreceived from the block 406 or even the addresses generated from theblock 502, while the block 508 serves to modify addresses received fromthe block 502 and/or the block 406 and even the block 504. The output ofthe block 506 is then provided as input to the mux 512, which alsoreceives, as input, the addresses generated by the block 502. The mux512 then selects one of its inputs and couples the same onto the bus 520for reception by other blocks of the block 74, as shown in FIG. 4.Similarly, the output of the block 508 provided as input to the mux 510,which also receives, as input, the addresses generated by the block 502.The mux 510 then selects one of its inputs and couples the same onto thebus 522 for reception by memories of the block 74, as shown in FIG. 4.

Thus, the Load/Store MFU can generate two addresses in parallel. Anaddress is computed by combining an address register and either aconstant or a value from the Scalar ALU MFU. A computed address canoptionally be wrapped around within the bounds of a circular buffer.Computed addresses are primarily intended for use in accessing memories,but may also be assigned to address registers or circular bufferregisters, or used as inputs to other MFUs.

FIG. 6 shows, in greater detail, the general structure employed forregister files and forwarding inside macro functional units,specifically in blocks 402, 404, 406, and 408. In FIG. 6, a plurality ofregisters 602, a plurality of muxes 604, a crossbar 606, a registerblock 608, a plurality of staging registers 610, a plurality offunctional units 612 and a plurality of muxes 614 are shown inaccordance with an embodiment of the present invention. The registers602 is shown coupled to the muxes 604, which are, in turn, shown coupledto the crossbar 606. The crossbar 606 is shown coupled to the registers610, which are, in turn, shown coupled to the functional units 612 andthe functional units 612 are shown coupled to the muxes 614. In general,the function of a mux is to select between the inputs it is provided andgenerate the selected input. The output of the crossbar 606 is alsoprovided to other blocks of the FIG. 4. While a particular number ofunits, muxes and/or registers is shown in FIG. 6, other number of thesestructures may be employed.

The structures of FIG. 6 are coupled together in the manner showntherein. The muxes 604 are shown to receive an additional input fromother blocks of FIG. 4, at least two such inputs, as well as the outputof the muxes 614.

The registers and feedback paths (coupling) of FIG. 6 offers a uniqueorganization to optimize the tradeoff of area, energy, and performance.This organization has three main characteristics:

-   -   Register files that are visible to the assembly language and        have more than a few registers are broken into two subsets: a        few registers are implemented with full accessibility, while the        remaining registers are implemented with more limited        accessibility. Only the first four registers (numbered 0        through 3) support full accessibility in most cases. For machine        operations involving this register file, any and all of the        fully accessible registers may be selected simultaneously as        sources and destinations of the operations. In contrast, the        registers with limited accessibility share only a small number        of read and write ports between them. In the registers with        limited accessibility have at most two read ports and one write        port that they share. This arrangement gives most of the        benefits of a register file with a large number of read and        write ports without needing more than one or two read/write        ports for most of the registers in the set.    -   At the inputs of every functional unit are “staging registers”.        Before a functional unit is used in a clock cycle, its input        staging registers must be set at the end of the previous clock        cycle with the proper input values. Functional units that cannot        be in use simultaneously can be grouped together to share the        same staging registers, so as to reduce the total number of        registers. If none of the functional units that share the same        staging registers is needed in a clock cycle, the previous        values of the registers are held, thus eliminating transition        power consumption in those functional units for that cycle.    -   Forwarding among functional units is implemented in two stages.        First, the next values of the fully accessible registers are        selected through multiplexors, along with the value or values,        if any, to write to the registers with limited accessibility. In        the second stage, the next values of the fully accessible        registers, and the values from the read ports of the registers        with limited accessibility, are together fed to a crossbar that        selects the values to be written to the staging registers at the        end of the clock cycle (and thus for the functional units in the        next clock cycle). This organization minimizes the number of        inputs to the crossbar, greatly affecting its size, at the        possible cost of increased delay from going through two        multiplixing stages rather than one. Between the write and read        ports of the registers with limited accessibility, forwarding        may or may not be implemented. If forwarding is not done here,        one extra cycle of latency will be apparent between an operation        that writes one of these registers and a subsequent operation        that reads it.

FIG. 7 shows further details of the block 408, in high-level blockdiagram form and accordance with an embodiment of the present invention.In FIG. 7, a vector register block 702 is shown coupled to an N ALUsblock 704, a vector element shifter block 706, a vector element selectorblock 708, a 2N and N bit converter block 710, an N ALUs block 712 and a2N multipliers block 714. In FIG. 7, the block 408 is further shown toinclude a vector registers block 716 coupled to an N adders block 718,an N shifters block 720, a vector sum block 722, an N 3-input addersblock 724, a 2N and N bit converter 726, a mux 723 and a mux 732. Theblocks and muxes of FIG. 7 are coupled together in the manner shown inFIG. 7. the block 702 is coupled to other blocks of FIG. 4 and isfurther coupled to the blocks 704-714. The block 716 is shown to receiveinput from the block 406 and from the output of the mux 732, the block710 and the block 714 as well as the block 724. The block 702 is showncoupled to a mux 704 and the latter is further coupled to the blocks 712and 726. Generally, the circuits or blocks of FIG. 7 operate on vectortype of values, such as an N number of M-bit value with M being aninteger number of bits, in parallel.

The mux 732, receives as input, outputs generated by the block 718 and720 and the mux 730 receives inputs generated by the blocks 704 and 706and further generates an output that is received by the block 702. Theoutput of the blocks 708 and 722 are provided to the block 406. N, asused herein is an integer value, for example, N ALUs is an N number ofALU circuits.

The blocks 702-714 and the mux 730 generally perform a multiplyaccumulate (MAC) function, whereas, the blocks 716-726 and the mux 732perform an ALU function, however, the number of bits, in parallel, onwhich such MAC and ALU functions are performed is generally N timesgreater than the number of bits processed by the block 406. The blocks704 and 712 are segmentable, that is, they are capable of selectablysegmenting add operation. For example, in the case where N 32-bits arebeing processed, in parallel, in addition to being able to perform N32-bit add operations, each ALU block is capable of performing 2N 16-bitadd operations, or 4N 8-bit add operations. The block 714 functions inthe same manner as that of block 1110 of FIG. 11, which will bedescribed shortly. The blocks 710 and 726 function to convert N 32-bitvalues to N 40-bit values, or a 2N 16-bit values to 2N 40-bit values. Inone example, a 32-bit value is converted to a 40-bit value and inanother example, a 16-bit value is converted to a 40-bit value, thus,offering bit conversion capability.

The block 706 shifts a vector value, i.e. an N M-bit value, to the rightor left by an integer value. An example of a vector shift would be totake a vector such as

-   -   <a0, a1, a2, a3, a4, a5, a6, a7>,

in this case eight values, and return the vector

-   -   <a1, a2, a3, a4, a5, a6, a7, 0>

or perhaps

<0, 0, 0, a0, a1, a2, a3, a4>.

These operations would not usually be interpreted as any sort ofmultiplication or division. The block 708 allows choosing a singleelement of a vector value, for example, a particular byte (eight bits)can be selected out of the vector value.

The block 720 functions in a similar manner as the block 706 and theblock 726 functions in a similar manner as the block 710. The output ofthe blocks 712 and 726 are selectively provided to the block 702,through the mux 704 and the output of the blocks 706 and 704 areselectively provided to the block 702, through the mux 730. Furthermore,the outputs of the blocks 720 and 718 are selectively provided to theblock 716 through the mux 732.

The block 722 performs an addition operation on a vector basis, whereas,the other blocks of the block 408 operate on an element basis. That is,the block 722 adds all of the elements of a single vector together andthe blocks that operate on an element basis perform an operation on oneor more of a selected and corresponding element(s) of different vectors.

The blocks 710 and 726 each allow a conversion from N or 2N,selectively. Further shown in FIG. 8, the output of the block 804 is fedback to the input of the block 802

FIG. 8 shows further details, in block diagram form, of the block 404,in accordance with an embodiment of the present invention. In FIG. 8,the block 404 is shown to include a mask control registers block 802, amask generator block 804, a mask registers block 806, a vector registersblock 808 and a vector byte mask permutation block 810 coupled togetherin the manner shown in FIG. 8.

The block 802 is shown to receive input from other blocks of FIG. 4 andgenerates an input to the block 804, which is shown coupled to the block806. The block 806 is shown coupled to the block 801 and is furthercoupled to the other blocks of FIG. 4, as well as the memory 312. Theblock 808 is shown coupled to the memory 312 and other blocks of FIG. 4.The block 810 is shown coupled to receive input from the blocks 806 and808.

In one example, the block 404 has a register file, the block 808, ofN*32-bit vector registers, for the same N as the block 408. The block806 of the block 404 includes mask registers of size N*4 bits. Each bitof a mask register corresponds with one byte of a vector register. Whenan N*32-bit vector is stored to external shared memory, an N*4-bit maskcan be supplied to indicate which bytes of the vector are actually to bewritten to memory. (Memory bytes corresponding to a zero bit in the maskare left unchanged.) A mask generator function computes a 4*N-bit maskbased on the setting of a mask control register.

The block 404 can permute the 8*N bytes of two vector registers tochoose 4*N bytes. In the general case, the specific permutation iscontrolled by the value of a third vector register. Certain “precoded”permutations do not require the use of a control vector; these includeall funnel shifts left and right of the two input vector registers. Atthe same time that the 8*N bytes of two vector registers are permuted,the 8*N bits of two mask registers can be identically permuted tomaintain the same bit-for-byte correspondence between mask and vectorvalues.

The blocks of FIG. 8 operate on a vector value basis. The block 810allows rearranging of vector values, such as previously indicated. Thisis done using permutations, which is further described with reference toFIGS. 9 and 10. The block 810 provides information regarding whichpermutation is to be expected. Similarly, a permuted mask from blocks804 and 806 indicate which permuted masks are to be provided. Generally,there is one mask bit for every byte to be stored.

The blocks 802, 804, 806 and 810 of FIG. 8 cause the ability torearrange addresses in memory to suit the particular applicationundergoing execution. In prior art techniques, rearranging is typicallyperformed automatically, however, in the embodiments of the presentinvention, the programmer, in accordance with the program or code, canprogrammably perform rearrangement, as desired. This allows for a nearinfinite sets of rearrangements pursuant to the programmer's needs,which prior art techniques simply do not offer, i.e. the capability torearrange is predetermined and includes a predetermined set ofrearranging possibilities. Thus, generating masks pursuant to theprogram being executed offers further flexibility vis-à-vis rearrangingof addresses in memory.

SIMD is an acronym for _Single Instruction, Multiple Data_, and MIMD is_Multiple Instruction, Multiple Data_. These are standard terms incomputer architecture and programming known to those skilled in the art.

FIGS. 9 and 10 show further details of the permutation circuit of theblock <number>. where <number> is the number for the “Vector Byte+MaskPermutation” box. The block 404 has a functional unit that performs apermutation of two vectors to generate a permuted result vector, asshown in FIGS. 9 and 10. The circuit used to perform the permutation canbe described in a general way as taking two input vectors A and B, eachof N units, and generating an output vector Z, also of N units, where aunit is any arbitrary but uniform number of bits, and where N isrequired to be a power of 2. Let K be the log base 2 of N. Thepermutation circuit has K+1 stages, each with N switch boxes of aparticular type, as shown in the figure. There are three types of switchboxes overall, called “type A”, “type B”, and “type C”. Switch box typeA is used only in the first stage; switch box type C is used only in thelast stage; and all stages in the middle employ only switch box type B.The connections supported by each type of switch box are shownseparately. Between the switch boxes of each pair of adjacent stages isa butterfly exchange, starting with an exchange of distance 1 andworking up to an exchange of distance N/2. The settings of the switchboxes are all determined independently by a “control vector”, which is athird input to the permutation circuit. Since the setting of each type Aand type C switch box requires only a single bit to specify, and thesetting of each type B switch box requires exactly two bits to specify,a complete control vector needs 2*K*N bits. The control vector may beimplied entirely from the permutation instruction executed, or it may besupplied in part or in full by the program in some way.

FIG. 11 shows further details of the components of the block 406, inblock diagram form and accordance with an embodiment of the presentinvention. In FIG. 11, a registers block 1102 is shown coupled to an ALUblock 1104, a bit converter block 1106, an ALU block 1108 and amultiplier block 1110. The block 406 is further shown to include aregister block 1112, a shifter block 1114, an adder block 1116 and a bitconverter block 1118. Muxes 1122, 1120 and 1124 are also shown in FIG.11. The muxes and blocks of FIG. 11 are coupled together in the mannershown therein.

The block 1102 is shown coupled to the memory 312 and other blocks ofFIG. 4 and receives input from the mux 1122 and the mux 1120. Theshifter block 1114 provides one of the inputs of the mux 1122 and theblock 1104 provides the other input thereof. The mux 1120 receives itsinputs from the blocks 1118 and 1108. The block 1114 is further showncoupled to the block 1102 and the mux 1124 is shown to receive inputsfrom the blocks 1112 and 1102 and generates an output to the block 1114.

The block 1112 is shown coupled to the block 1116, which generates anoutput provided as input to the block 1112. The block 1118 is showncoupled to the block 1112 and blocks 1106 and 1110 are shown coupled tothe block 1112.

The blocks 1102, 1104, 1106, 1108 and 1110 and the mux 1122 cause an ALUfunction to be performed while the blocks 1112-1118 and the mux 1124cause an a multiply-accumulate (MAC) function to be performed.

The blocks 1104 and 1108 are ALUs and perform such functions and theiroutput is selectively, through the muxes 1122 and 1120, provided asinput (or feedback)to the block 1102. In every clock cycle, two ALUoperations may be performed. The block 1110 performs a multiply functionand produces an output that is provided to the block 1112, which iscapable of processing a higher number of bits, in parallel, than that ofthe block 1102. For example in the case where the block 1102 has a32-bit capability, the block 1112 has a 40-bit capability. The block1112 serves an accumulator register, i.e. adding inputs accumulatively.

The block 1106 converts an N-bit value to an N+X, where X is an integervalue. For example, a 32-bit value can be converted to a 40-bit value.The block 1114 shifts a value by a predetermined number of bits andpasses the result to the block 1102, through the mux 1122.

The block 1118 converts from a higher number of bits to a lower numberof bits, such as 40 bits to 32 bits. The block is coupled to the block408. The block 406 can execute two ALU operations in parallel on valuesfrom the block 1102. In place of the first ALU operation, an N-bit shiftoperation may be performed, or a conversion of an N-bit value to a X-bitvalue to be stored in the block 1112. In place of the second ALUoperation, a multiplication may be performed by the block 1110 and theresult stored in one of the registers of the block 1112.

The block 406 can, in parallel, perform a 40-bit shift, a 40-bitadd/subtract, and a conversion of a 40-bit value to a 32-bit one to bestored in one of the Scalar ALU MFU's 32-bit registers.

Further details of one of the N-type sub-processors, such as the block78 will now be discussed with reference to figures to follow. It shouldbe noted that the blocks 406 and 404 of FIG. 4, relative to the W-typesub-processor, are common to N-type sub-processors, such as the block78.

FIG. 12 shows a high level block diagram of the details of the block 78in accordance with an embodiment of the present invention. In FIG. 12,the block 78 is shown to include a data path unit (DPU) block 1202, apath to memory block 1204 and a controller, sequencer and data addressgenerator (DAG) block 1206. Blocks 1204 and 1206 are in common with andfound in the blocks of the W-type sub-processors. The block 1206 isgenerally functionally the same as the block 402.

FIG. 13 shows still further details of the block 78, in high level blockdiagram form, in accordance with an embodiment of the present invention.In FIG. 78, a store unit block 1302 is shown coupled to an X unit block1304, which is, in turn, shown coupled to a load unit block 1306. Theblock 1304 is generally functionally the same as the block 404 and thus,is discussed in further detail hereinabove.

The block 1306 is shown further coupled to the macro function blocks1340, which is, in turn, shown coupled to the block 1302 through a macrofunction bus 1310. The block 1302 is shown to include a store buffer1314, a store buffer 1312 and a bus interconnect block 1308. The block1302 generates an output provided to memory, such as the memory 312 andtherefore coupled accordingly through the block 1314. The block 1304 isshown to receive input or be coupled to memory, such as the memory 312.The block 1306 is shown to include a load buffer 1320, a load buffer1318 and a bus interconnect block 1316, which is coupled to the blocks1340.

The blocks 1340 are shown to include a Galois field MAC block 1322, aspecial ALU block 1324, a combiner block 1326, a memory 1328, apuncturing/depuncturing block 1330, an interleaver block 1332 and anviterbi block 1334, which are each shown coupled to the bus 1310. Theblocks 1322-1332 are each shown to receive input from or be coupled tothe block 1316. The block 1334 receives input from the block 1332 and iscoupled to receive and generate data thereto.

The flow of data is such that data or information flows in from andthrough the block 1306 to the blocks 1340 and then to the block 1302 andout onto memory. In this manner, a pipeline affect is introduced whereinmultiple operations overlap and are processed concurrently, in apipeline fashion. For example, information may be loaded by the block1306 while information is being stored into memory by the block 1302.Data is stored in the blocks 1320 and 1328 of the block 1306 after beingreceived by the block 1304 from memory and subsequently provided to andprocessed by the blocks 1340, the details of which will be discussedshortly with respect to subsequent figures.

Upon completion of processing by the blocks 1340, the processed data isprovided to the block 1302, through the bus 1310, and stored in theblocks 1312 and 1314 wherein they are stored until coupled to bereceived by memory. The buffers of the blocks 1314, 1312, 1318 and 1320are of a predetermined width or number of bits, in parallel. In oneexample, each of these buffers is 256 bits wide, however, other numberof bits may be employed.

A value or data, that may have been processed by the blocks 1340, may bemoved from the block 1302 to the block 1306 for re-use. Furthermore,data may be received by the block 1304 from memory and then moved totthe block 1306 for processing thereof. Further details of each of theblocks 1340 are now presented. The blocks 1314 and 1312 cause a doublebuffering effect, which assists in reducing “stalling” commonlyexperienced in pipelining operations, as do blocks 1318 and 1320.Stalling results from access of blocks 1302 and 1306 simultaneously bymemory. In another embodiment, the blocks 1314 and 1312 may be one blockand the blocks 1318 and 1320 may be one block.

A latency may be associated with an operation or a pipeline affect maybe present. The latency may result from each of the blocks with theblocks 1340.

FIG. 14 shows further details of the block 1322 in accordance with anembodiment of the present invention. In FIG. 14, a Galois field block1402 is shown coupled to an XOR/Clr circuit 1404, which is, in turn,shown coupled to an accumulator register block 1406. The block 1402 isshown to generate a Galois field output signal 1408 which serves asinput to a Galois field mux 1410, which further receives another input,generated by the output of the block 1406 and referred to as theaccumulator register block output signals 1412. The signals 1408 and1412 serve as inputs to the mux 1410 for selectively generating a Galoisfield MAC output signal 1416, which is coupled onto the bus 1310 of FIG.13. A select signal 1414, which serves as another input to the mux 1410,functions to select one of the signals 1408 and 1412 for generation ofthe signal 1416. Accordingly, either the output of the block 1402, whichis effectively the result of the Galois field operation is provided asthe output of the block 1322 or the Galois field MAC operation result isprovided as the output of the block 1322.

The output of the block 1406 is shown coupled to the circuit 1404 asanother input thereof. The output of the block 1404 is provided to theblock 1406, such coupling effectuates the MAC part of the Galois fieldMAC operation. The block 1404 effectively performs an XOR multiplyoperation typically used in Galois field MAC operations.

The block 1402 is shown to include a register block 1420 and a registerblock 1422, which are shown coupled to an Xor tree block 1424. The block1420 is further shown to include a register block 1426, a Galois fieldmultiply iteration 1 1428, a register block 1430, a Galois fieldmultiply iteration 1 1432, a register block 1434 and a register block1436. While not shown in FIG. 14, an additional number of registerblocks, such as the blocks 1434 and 1436 are included and coupled, inseries, between the blocks 1434 and 1436.

The block 1424 is shown coupled to the block 1426, which is, in turn,shown coupled to the block 1428, which is, in turn, shown coupled to theblock 1430, which is, in turn, shown coupled to the block 1432, whichis, in turn, shown coupled to block 1434, which is coupled to either theblock 1436 or one or more register blocks intermediately located betweenthe blocks 1434 and 1436.

In FIG. 14, the blocks 1420 and 1422 receive input from the block 1306and in another embodiment may be combined into one block. The block 1402generally performs Galois field processing known to those of ordinaryskill in the art and the remaining blocks of FIG. 14 cause performanceof a MAC operation. The blocks 1426, 1430, 1434 and 1436 serve asdifferent iterations of a Galois tree and it has been experienced thatin a worst case scenario, the number of iterations is eight thusrequiring eight register blocks. The multiply portion of the MACoperation is generally performed by an XOR operation performed by thecircuit 1404 and the block 1406 serves as the accumulator function. Thecircuit 1404 receives its input from the last iteration of the Galoisfield operation performed by the block 1402 and in the case of FIG. 14,the block 1436.

In operation, the block 1322 operates on an N-bit value or data, such asan 8-bit value, and based on the same generates an N-bit value or databy shifting the original value eight ways based on another N-bit value.The N-bit values are then XORed by the block 1404 until the result isreduced to N bits with a reduction constant and optionally added withthe contents of an N-bit accumulator register, such as a value in theblock 1406. A “Clear” operation may also be performed by the block 1406.Example of applications employing Galois field MAC operations andtherefore block 1322 include but are not limited to cyclic redundancycode (CRC) operations, convolutional encoder operations, scramble codegenerator operations and others.

FIG. 15 shows further details of the circuitry included in the block1324, in high-level block diagram form and accordance with an embodimentof the present invention. In FIG. 15, muxes 1504 and 1502 are showncoupled, respectively, to an A register block 1508 and a B registerblock 1506. The block 1508 stores a value, referred to as A and theblock 1502 stores a value referred to as B and these A and B values aredata to be operated thereon by the block 1324. The A and B values areeach N-bit wide.

The blocks 1508 and 1506 are shown to generate inputs to a conditionalregister block 1512 and further shown coupled to generate inputs to theadd/sub/Abs/diff/conditional add-sub/multiply (AGU) block 1510, which,in turn, generates input to the output register block 1514. The block1514 is shown coupled to a mux 1516, which is, in turn, shown coupled toan adder 1518. The adder 1518 is shown coupled to anaccumulator-register block 1520, the output of which is shown to serveas another input of the adder 1518. Another output of the block 1520 isshown to serve as input to a mux 1522, which receives, as another inputas output of the block 1514. The mux 1522 generates an output 1530 whichis coupled to the bus 1310. Some of the inputs to the muxes 1504 and1502 are received from the block 1316.

Each of the muxes 1504 and 1502 is shown to receive four inputs. One ofthe inputs of the mux 1504, dp, is received from the block 1306, as isthe input, dp, of the mux 1502. Another input of the mux 1504 comes froma series of the lowest-order bits of an output of the block 1514, asdoes one of the inputs of the mux 1502. Another input of the mux 1504comes from the highest-order of bits of the same output of the block1514. Yet another input of the mux 1504 is a value ‘0’. One of theinputs of the mux 1502 is the value ‘1’ and another one of its inputs isthe value ‘−1’. The values ‘0’, ‘1’ and ‘−1’ are provided in an effortto expedite the operations performed by the block 1324 in that it hasbeen experienced that these values are repetitively utilized in variousoperations and therefore there presence increases system performance. Itshould be noted that there might be a plurality of the blocks 1510utilized for increased performance. The block 1324 is organized as shownin FIG. 15 to allow many of the operations performed thereby to beperformed in a single clock cycle.

In operation, the blocks 1510 and 1512 operate on the A and B valuesprovided by the blocks 1508 and 1506, respectively. Two other inputs tothe mux 1516 are generated by a reduction operation block within theblock 1520 (not shown in FIG. 15), which will be discussed shortly. Fornow, these two inputs are referred to as ‘neighbor-acc-reg’ and‘reduction-acc-reg’, each being 2N wide.

The block 1512 is a 2N wide register that allows conditional add orconditional subtract operations to be performed by the block 1510 foruse in despreading operations. The block 1512 essentially modifies the Aand B values for use by the block 1510.

The mux 1522 allows essentially the output of the block 1510 upon havingbeen stored by the block 1514 to be selectively provided to the block1302, through the signal 1530, and as determined by a select signalprovided as yet another input to the mux 1522. Otherwise, the result ofthe block 1510 undergoes an accumulation-add operation, the final resultof which is stored in the block 1520, through the blocks 1518 and 1520prior to being provided to the block 1302.

The block 1324 is an N-layer ALU including one or more ALUs that supportthe following operations:

-   -   N add/subract operations wherein two N-bit values are operated        thereon to generate sum or differences thereof    -   N-bit XOR on two input values    -   Maximum/Minimum operation on two N-bit input values    -   Maximum* operation on two N-bit input values such that the        result thereof is calculated as follows: max(a,b)+constant (from        memory or a small preloded look-up table)    -   Conditional Add-subtract: This function, which, in general,        results from use of the block 1512, conditionally adds or        subtracts a stream of N-bit values depending on the input code.        The input code is pre-loaded into a control register. A ‘1’ in        the input code results in a subtract operation an ‘0’ results in        an add operation. The output is available in a 16-bit        accumulator register. There is also support for a “gather        “operation from other special ALUs that support this operation.    -   SAD using the same accumulator as in the conditional        add-subtract operation.    -   N×N multiply

The block 1510 is common to the W-type sub-processor wherein each block1510 is capable of reading at least 128 bits and thus, the two blocksare capable of reading at least 256 bits of data every clock cycle whenthere is no contention in memory.

FIG. 16 shows a block diagram of a reduction circuit block 1602,included within the block 1520, in accordance with an embodiment of thepresent invention. In FIG. 16, an M-stage accumulator-register circuit,the details of each of the accumulator-register circuits of which areshown in the acc-reg block 1610 is shown. For example, the acc-regcircuit block 1602 includes four of the blocks 1610 coupled in themanner shown in FIG. 16. Similarly, each of the acc-reg circuit blocks1604-1608 include a four stage acc-reg circuit, such as that of block1610. The output or result of each of the stages within each of theblocks 1602-1608 is used as input to the next stage and therefore addedto achieve an accumulation. The blocks 1602-1608 are each shown toinclude 4 stages or 4 blocks such as the block 1610 but other number ofblocks or stages may be employed.

The result of each of the blocks 1602-1608 is made available to anotherblock. For example, the result of the block 1602 serves as input to theblock 1604, the result or output of the block 1604 serves as input tothe last acc-reg block within the block 1608 and the result or output ofthe block 1606 serves as input to the block 1608. Because the results ofthe blocks are provided in a forward manner and simultaneously with theaccumulation of the stages within a block, only seven cycles arerequired to perform a reduction operation when a four-stage acc-regblock is employed.

The block 16 is comprised of a mux coupled to an accumulator. The mux isa 2:1 mux selecting one of two inputs to be provided to the accumulator.One of the two inputs of the mux of block 1610 is provided by the outputof the block 1514 and the other input is the result of theprevious-stage acc-reg block. In this manner, the reduction function ofFIG. 16 is flexible in its manipulation of data. Each of the inputs froman immediately preceding output of a stage is referred to as a‘neighbor’ signals 1616 generating the neighbor-acc-seq input to the mux1516. The output of the some of the stages generates thereduction-acc-seg to the mux 1516 and is referred to as the ‘reduction’signals 1618. The output of the last acc-reg block of the block 1608generates the output 1620 coupled to the mux 1530. The reduction circuitof FIG. 16 results in minimal clock cycles for performing a reductionoperation while saving power consumption.

FIG. 17 shows further details of the circuitry included in the block1326, in high-level block diagram form and accordance with an embodimentof the present invention. In FIG. 17, the block 1326 is shown to includeshifters 1702-1712 for shifting the data input received from the block1306. In one embodiment, the input 1700 is 128 bits, however, othernumber of bits may be employed. The output of each of the shifters1702-1712 is shown coupled to a register bank block 1714. The shifters1702-1712 generate different combinations of bits of the input 1700.

The block 1714 includes a plurality of registers including the registers1716 through 1746 that used to create a combination of output of theshifters 1702-1712. For example, the lower eight bits of each of theshifter 1702-1712 output can be made to go through a mux to selectivelychoose which of the lower eight bits are to be ultimately generated.Thus, each of the registers of the block 1714 can arbitrary select amongan “interesting position” of shifted bits. The interesting position isdetermined by the output of each of the shifters 1702-1712. The outputof the block 1714 is provided to the bus 1310.

Thus, in one embodiment of the present invention, the block 1326comprises four 20-bit and two 24-bit input registers. It includes eight16-bit registers where random 32, 16, 8 and 4-bit combinations of bitsfrom its input registers is created and stored. The block 1326 can beused in three modes: Using two specific 20-bit registers for outputgeneration; 2) Using four 20-bit registers for output generation; or 3)Using all seven registers for output generation. The shifters 1702-1712include input registers not shown due to the known structure andfunction of a shifter by those skilled in the art.

In order to reduce the hardware or number of blocks or circuits requiredto perform the combining function of the block 1326, each bit in the32-bit output register can only be filled from the least significant8-bits in the two 20-bit registers in the first mode, the 4 leastsignificant bits in the four 20-bit registers in the second mode, andthe 2 least significant bits from the four 20-bit registers and 4 leastsignificant bits in the 24-bit registers in the third mode. Randomcombinations from the input registers is a two-step process where thefirst step involves shifting the “interesting’ bit s to the leastsignificant positions from where random filling into the output registercan be allowed in that mode. In the example used herein with respect toFIG. 17, the block 1326 can create 16 combined bits every cycle whenpipelined with the shift operation on the input registers to get theinteresting bits into the least significant positions. Some combinationsof output may take multiple clock cycles.

The memory 1326 is a generic random access memory and will therefore notbe discussed in further detail. Suffice it to say however, that the sizeof the memory is based upon the applications for which the N-typesub-processor is to be used.

FIG. 18 shows further details of the circuitry included in the block1330, in high-level block diagram form and accordance with an embodimentof the present invention. In FIG. 18, a one-word register 1802 is shownto include 8 bit positions, each bit position 1804 capable of beingmodified by a bit select circuit 1806. Such modifications include butare not limited to inserting a ‘0’, inserting a ‘1’, NOTing the bit,which is the equivalent of inverting it or to not modify it at all,which is the equivalent of a “NOP” or no-operation. The one-wordregister is repeated, i.e. word registers 1810-1820 each store andmodify a word, as the register 1802.

Thus, in the example of a 16-bit word and 8 words, the modification ofeight 16-bit words is performed in one clock cycles, unlike traditionalDSPs which need multiple cycles for performing the same. Themodification or puncturing/de-puncturing of each bit of the words iscontrolled by the mux 1824 and the flip-flop 1826 coupled to each otherand the register 1802 in the manner shown in FIG. 18. The registers1810-1822 are also similarly coupled to other mux and flip-flopcircuits. A mode select bit selects which of the four inputs of the muxto select and it is generated from the instruction code. Two of theinputs 1828 to the mux 1824 also come from the instruction code,whereas, two other of the mux inputs are from memory, one of which maybe an inverted version of the other, as shown in FIG. 18.

The input to the circuits of the block 1330 are generated from the block1332, which will be discussed shortly but for now, generates eitherfully interleaves, partially interleaves or un-interleaves N-bit wordsto the block 1330. In one example the operation is on 256-bit words, inwhich case, the block 1330 operates on 16-bits at a given time. Aprefetched control word is used to decide which bits within the 16-bitword must be inverted. Optionally, a ‘0’ or a ‘1’ value is entered intospecific bit positions in addition to inversion.

FIG. 19 shows further details of the circuitry included in the block1332, in high-level block diagram form and accordance with an embodimentof the present invention. In FIG. 19, a memory array 1902 is shown toreceive an input 104 from an input device, through the bus 1316, and aread enable input 1906, through the bus 1316 and further receive inputfrom a control row-column address generation block 1908 to generate anoutput device signal 1910, which is provide to the block 1302. In oneexample, the block 1902 includes a memory array made of 128×16 bits.Data can be written to or read from the block 1902 either on a row basisor a column basis. That is a row of the memory array of the block 1902may be read or a column of the memory array of the block 1902 may beread. Additionally, data can be written on a row-basis yet read on acolumn basis and visa versa.

FIG. 20 shows further details of the circuitry included in the block1334, in high-level block diagram form and accordance with an embodimentof the present invention. In FIG. 20, a branch metric unit 2002 is shownto receive input from the block 1332 and shown coupled to anadd/compar/select block, which is shown coupled to a survivor memoryblock 2012, which is, in turn, shown coupled to a mux 2020, whichgenerates a output 2022 coupled to the bus 1310. The mux 2020 is furthershown to receive another input from the output of an accumulator 2018,which receives input from a mux 2016. Optionally, asum-of-absolute-differences (SAD) block 2008 and a despreader (forde-spreading) block 2010 are used to generate an input to the mux 2016.In the absence of blocks 2008 and 2010, the mux 2016, the block 2018 andthe mux 2020 would not be used. A local memory 2006 is shown coupled tothe block 2004. The block 2002 performs a branch metric calculationknown to those who are familiar with Viterbi coding/decoding. Survivorpaths, also known to those who are familiar with Viterbicoding/decoding, are stored in the block 2012.

The block 1334 is capable of executing turbo-decoder, SAD anddespreading functions. In one example, 32 to 256 add-compare-selectoperations can be performed, in parallel, by the block 2004, on 16-bitbranch and path metric values generated by the local memory 2006. In oneexample, the size of the local memory 2006 is 1 kilobits and 16kilobits.

There may be a plurality of blocks 2004 included in the block 1334 eachof which may include 8-bit signed adders. Additionally, each can includea compare and a select block that returns the winning path and thedecision bit. The add-compare-select operations result in a winning pathand decision bits. The winning path can be shared with neighboringblocks 2004 using a “multi-cast' interconnect scheme for going down thetrellis. Decision bits with the winning branch and path metric valuesare stored for backtracking.

The block 2008 uses four eight-bit ALUs, in one example, four absolutedifferences of which can be calculated every cycle. A reduction tree isbuilt into the block 2004 to accumulate the absolute differences into a16-bit accumulator. The multi-cast network can be used to send thesevalues across for further reduction. A total of 128 8-bit (64 16-bit)blocks 2008 are possible per clock cycle. However, it is believed thatthe effective utilization considering all of the overheads might resultin a lower number.

The ALUs implement the same conditional add-subtract function that thespecial ALU block implements and discussed hereinabove. The control bitsneeded for despreading must be loaded into the local memory from whereit is fetched and stored in a register. The results are accumulated intoa 16-bit accumulator from where I can be transferred to other blocks2004 for reduction operation thereon. With despreading, in one example,it is possible to perform 128 simultaneous conditional add-subtracts ina single cycle. The energy per transition in this unit is higher thanthat used for the special ALU serving some general functions other thandespreading and SAD. For smaller number of fingers or for lower ratemotion estimation, the special ALU is a more power efficient option.

FIG. 21 shows an example of programming flow and tools using theprocessor 22 in accordance with an embodiment of the present invention.FIG. 22 shows an example of the scalability of embodiments of thepresent invention. For example, in FIG. 22, there are clusters 2202 ofsub-processors of N-type and W-type shown to be interconnected using thebus 2204. Each cluster 2202 includes two or four sub-processors. The bus2204, in one example, is a standard SoC bus. By maintaining anhierarchical design methodology, interconnectivity is addressed.

Scaling of the processor 20 results in clusters of four sub-processorswith separate buses for each cluster, otherwise, four sub-processors canshare a single memory. Scalability with respect to processors hasgenerally been by way of increasing the number of processors orincreasing the frequency or speed of the processor. However, complexapplications require scaling beyond that which has been previously done.In the present invention, the W type and N type sub-processors aremodified so that four such sub-processors forming a processing canprocess a single application.

Accordingly, the processor 22 is equipped with capability to run controland sequential DSP code found in targeted applications more efficientlythan RISC and Super Scalar processors directly based on compilation fromC code. At the same time, it is designed to take advantage of automaticcode generation techniques used in RISC and Super Scalar processors forlegacy and light applications. Furthermore, the processor 22 works withmatured and industry standard software tools like Simulink forapplication mapping and development. Moore's Law can be utilized toenhance performance of the processor 22. The processor 22 is not only ahighly parallel machine but also a heterogeneous multi-processor. It isa proven fact in both industry and academia that parallel heterogeneousmulti-processors are required to address demanding multimedia andcommunications applications. It allows utilization of many of theautomatic code generation techniques used in VLIW without using anypower and area inefficient techniques. It is optimized to take advantageof repeating patterns based on compilation of control code from C. Thissignificantly reduces control power and makes it possible to runcompiled serial code efficiently. Additionally, the processor 22'sprogramming model is designed to suit a large community of DSPprogrammers using tools familiar to them like Simulink. Its developmentflow provides the means for efficient C-compilation of the control andsequential DSP code. Also an extensive set of library of highlyefficient communications and multimedia kernels are provided. Examplesare parameterized library of FFT, IDCT, RRC, Viterbi, VLC, 2D/3DGraphics, Turbo codec, and De-scrambler.

The data path design in the processor 22 successfully integrates varyinginterconnect structures connecting functional units of varyinggranularity to effectively address a focused yet highly lucrativeapplication mix.

The scalability of the processor 22 is designed to fit all applicationsin a single block (time multiplexed) with nearest neighbor connectionswithin a block based on standard SoC bus. Considerable amount ofinefficiency and all the system level non-determinism is reduced becausemultiple blocks can be used to process multiple applications without anyproprietary communication between them.

FIG. 23 shows a chart presenting some of the benefit the scalability ofthe present invention.

Although the present invention has been described in terms of specificembodiments, it is anticipated that alterations and modificationsthereof will no doubt become apparent to those skilled in the art. It istherefore intended that the following claims be interpreted as coveringall such alterations and modification as fall within the true spirit andscope of the invention.

1-20. (canceled)
 21. A heterogeneous, scalable processor, said processorcomprising: a first heterogeneous programmable integrated circuitsub-processor configured for 16, 24, 32 and 64-bit processing; and asecond heterogeneous programmable integrated circuit sub-processorconfigured for 8, 4 and 1-bit processing, wherein at least one of thefirst and second sub-processors include one or more functional unitseach including a memory and configured for rearrangement of data valuesto and from the memory, and wherein each of the first and secondsub-processors can only execute one function at a time with an internalcontrol block configured to synchronize an order of function execution.22. A computer implemented method correspond to the system of claim 1.23. A computer program product corresponding to the system of claim 1.